volcanoes

Volcanoes

In the year 79 Mount Vesuvius, a volcano in Italy, blew up. Hot, melted rock from deep inside the earth pushed up through the mountain. The top of the mountain exploded. Ash, cinders and stones buried Pompeii, a great city below the mountain.

Nearly two thousand years later Mount Vesuvius still spouts steam and ash. But not as much as it did long ago. In 1815 the same thing happened in Indonesia, a group of islands between Asia and Australia. Mount Tambora blew its top. Billions of tons of the mountain were turned into ash and thrown into the air. Winds carried the ash all around the earth. It made a cloud that blocked out the sun. The earth got colder and colder. The next year, 1816, was called the year without a summer. The New England states had six inches of snow in June, and there were frosts in July and August. That's how cold it was.

In 1980, in the state of Washington, the top of Mount St. Helens blew up. Before it did, the earth shook. There was a rumble and bang so loud, it was heard 300 miles away. When the mountain exploded, steam, gas and ash were thrown into the air. The top of the mountain was gone. It had turned into hot ash.

Lightning flashed inside the dark clouds. Huge trees were flattened by the blast. Here and there the heat started fires. The hot ash melted snow on the mountain and made a thick mud that flowed down into the valleys. The mud covered fields and forests. Lakes, ponds and rivers were filled with it. The mud buried animals, houses and people.

The eruption of Mount St. Helens was not a surprise. Geologists, people who study the earth, knew that the volcano had erupted about a hundred years ago. And it was bound to happen again. Geologists watch volcanoes for signs of an eruption.They listen for rumblings. Mount St. Helens had been rumbling off and on for more than a hundred years. Geologists knew that these rumblings were warnings. Geologists also measure earthquakes. Before a volcano erupts, there are usually earthquakes in the region.